Apiospora parallela
Stromata 1-2 x 0.2-0.5 µm, oblong to linear, formed between vascular bundles of the host tissue, at first immersed beneath the apidermis but becoming widely erumpent through splits in the substratum, often aggregated and sometimes coalescing, matt black, 1- to 3-loculate, the ostioles inconspicuous, the outer part composed of several layers of mid brown thick-walled textura angularis with cells to 6 µm diam, the inner part of cells varying from textura angularis to porrecta, often vertically elongated and hyaline to pale brown, ranging from 6-10 x 2-5 µm in size.
Anamorph: not known.
Ascomata 150-250µm diam, globose to shortly pyriform, often slightly flattened at the base, thin-walled, the ostiole conspicuously periphysate. Peridium 15-25 µm wide, composed of compressed and sometimes vertically elongated textura angularis. Interascal tissue composed of thin-walled filamentous paraphyses to 5 µm diam. Asci 80-110 x 13-17 µm, cylindrical to cylindric-clavate, short-stalked, the walls thin at all stages of development, the apex obtuse to rounded without clear apical structures, 8-spored. Ascospores arranged biseriately, (19-) 21-25 x 6-7 (-8) µm, narrowly clavate-ellipsoidal, often slightly curved near the base, hyaline, smooth- and fairly thin-walled, with a single septum near the base of the spore, lacking gelatinous appendages or sheath.
The species may be considered an extreme variant of A. montagnei with rather narrow ascospores, but more collections are needed of both taxa in order to assess infraspecific variation. A combination into Arthrinium, needed due to the abandonment of dual nomenclature, has not yet been made.
Known from dead stems of Calamagrostis in northrn Europe. Reported from an unidentified grass from VC2 E Cornwall and (with doubt) from Festuca vivipara from Skye (VC104 N Ebudes).